Cross Groove Type Constant Velocity Joint with Composite Groove Patterns

ABSTRACT

A constant velocity joint for a drive system comprises: an outer joint member having a plurality of inwardly facing outer ball grooves, the outer ball grooves consisting of a first group of grooves and a second group of grooves with composite or non-linear groove pattern; an inner joint member disposed inside the outer joint member and having a plurality of outwardly facing inner ball grooves consisting of a first group of grooves and a second group of grooves with composite or non-linear groove pattern, each inner ball groove of the inner joint member being coupled with a corresponding outer ball groove of the outer joint member generally in crossed pair; and a cage having circumferentially displaced cage windows to accommodate a plurality of balls therein. The groove patterns of the ball grooves can be a combination of skewed grooves and non-linear grooves, a combination of non-linear grooves such as a curved groove or a compositely shaped groove, or a combination of linear grooves and non-linear grooves.

FIELD OF THE INVENTION

The present invention relates to a cross groove type constant velocityjoint for use in a drive system, and more particularly, to a crossgroove type constant velocity joint having composite groove shapes,typically for use in a drive system of, for example, an automobile fortransmitting rotational torque between two rotating shafts thereof.

BACKGROUND OF THE INVENTION

A cross groove type constant velocity joint (hereinafter to be referredas a “cross groove joint”) is one type of constant velocity universaljoints used for transmitting rotational torque between the rotatingshafts (i.e., the driving shaft and the driven shaft), typically for thedrive system of automobiles. The cross groove joint includes an outerjoint member with a plurality of ball grooves formed on the innersurface thereof, and an inner joint member with a plurality of ballgrooves formed on the outer surface thereof, in which the correspondingball grooves of the outer joint member and the inner joint member areconfigured to pair with each other and slanted in opposite directionswith respect to the center or rotating axis of the joint.

FIGS. 1-2 illustrate one example of a conventional cross groove typejoint which retains six balls in the ball grooves for transmitting therotational torque between the outer and inner joint members to drive thedrive system. This cross groove joint includes an outer joint member 1with six grooves formed on the inner surface thereof, an inner jointmember 3 with six grooves formed on the outer surface thereof, six balls2 retained in the pared grooves of the outer and inner joint members fortorque transfer between the outer and inner joint members 1 and 3, and acage 4 configured to support the balls 2 to a plane bisecting the angleof articulation between the axes of rotation of the outer and innerjoint members 1 and 3.

In the structure of the conventional cross groove joint as shown in FIG.2, the outer joint member 1 has a plurality of (i.e., six) inwardlyfacing outer ball grooves 1 a alternately skewed with a skew angle δ inopposite directions relative to an axis of rotation of the outer jointmember 1. The inner joint member 3 positioned inside the outer jointmember 1 has a plurality of (i.e., six) outwardly facing inner ballgrooves 3 a alternately skewed with the same skew angle δ in oppositedirections relative to an axis of rotation of the inner joint member 3.The outer and inner ball grooves 1 a and 3 a face each other in crossedpairs with each of the balls 2 positioned between each crossed pair fortorque transfer between the inner and outer joint members 1 and 3. Asthe ball 2 is retained in the cage 4, the ball 2 is limited in a ballmovement range L2 in the circumferential direction of the joint, and theouter joint member 1 has a minimum thickness L1 on one side of themember. To secure the movement of the balls 2, the cage 4 includes aplurality of (i.e., six) cage windows 4 a with a dimension sufficient toaccommodate the ball movement L2. As a result, the width L4 of each cageweb 4 b must be designed to have a dimension at least the same or lessthan the minimum thickness L1 of outer joint member 1.

In an attempt to reduce a transmission error and to make the design ofthe joint more compact, the cross groove joints retaining eight ballshave been suggested. The eight-ball type cross groove joint known in theart typically has a basic structure generally the same or similar tothat shown in FIGS. 1-2, however, with the number of the balls and thenumber of the ball grooves of the outer and inner joint membersrespectively increased from six to eight. FIGS. 3( a) and (b) illustratea conventional cross groove joint with eight balls. Like the six ballcross groove joint, the eight ball cross groove joint includes an outerjoint member 11, an inner joint member 33, balls 22 for torque transferbetween the outer and inner joint members, and a cage 44 configured tosupport the balls to a plane bisecting the angle of articulation betweenthe axes of rotation of the outer and the inner joint member.

In the structure of the conventional eight ball type cross groove jointas shown in FIG. 4, the outer joint member 11 has a plurality ofinwardly facing outer ball grooves 11 a alternately skewed with a skewangle δ in opposite directions relative to an axis of rotation of theouter joint member. The inner joint member 33 placed inside the outerjoint member 11 similarly has a plurality of (i.e., eight) outwardlyfacing inner ball grooves 33 a alternately skewed with the same skewangle δ, however, oriented in opposite directions relative to an axis ofrotation of inner joint member 33. The outer and inner ball grooves 11 aand 33 a face each other in crossed pairs with each of the balls 22retained between each crossed pair for torque transfer between the innerand outer joint members. As the ball 22 is retained in the cage 44, theball 22 is limited in a ball movement range L22 in the circumferentialdirection of the joint, and the outer joint member 11 a minimum (least)thickness L11 on one side of the member. To secure the movement of theballs 22, the cage 44 includes a plurality of (i.e., eight) cage windows44 a with a dimension sufficient to accommodate the ball movement L22.As a result, the width L44 of each cage web 44 b must be designed tohave a dimension the same or less than the minimum thickness L11 ofouter joint member 11.

As the cross groove joint with higher balls (e.g., eight or more balls)can provide more compact design and secure a smoother and reliableoperation as compared to the cross groove joint with six balls, it wouldbe desirable to produce a higher ball (e.g., eight or more balls) typecross groove joint which has the same or equivalent durability as thathaving six balls. More specifically, if the cross groove joint witheight balls, for example, is designed to have the same pitch circlediameter (PCD) as the joint having six balls, the ball diameter of theeight ball joint can be reduced because the load on each ball groove andthe stress onto the cage web 44 b decreases by the increase of thenumber of the balls. In addition, the size of each cage window 44 a canalso be reduced compared to the joint containing six balls.

However, the higher ball (e.g., eight ball) type cross groove joint mayalso include certain shortcomings or disadvantages as described below,for example. Because the eight ball type joint includes more (i.e.,eight) cage windows 44 a, the thickness of the cage web 44 b is alsoreduced, and thus, the stress on the cage web 44 b becomes greater thanthat of the six ball type. Comparing to the joint with six balls havingthe same PCD, the increased amount of stress on the cage web (due to thereduction of cage web thickness) exceeds that of the decreased amount ofstress owing to the increase of the number of balls. Therefore, thehigher ball (e.g., eight ball) type cross groove joint may have aweakened strength and durability in the cage web, and thus, the loadbearing capacity of the joint can be deteriorated than that of theconventional six ball type joint.

SUMMARY OF THE INVENTION

In order to solve the above described and other shortcomings ordrawbacks known in the conventional cross groove joints, the presentinvention provides a cross groove joint (preferably, but notnecessarily, of higher ball type) with a compact and durable structure,in particular, with the strength of the cage web enhanced than that ofthe conventional cross groove joints as described above.

In order to provide an enhanced strength to the cage web of the crossgroove joint, the present invention provides a cross groove jointincluding an outer joint member with a plurality of inwardly facing ballgrooves and an inner joint member with a plurality of outwardly facingball grooves, in which the shapes of the ball grooves of the outer andinner joint member are configured to increase the thickness and also themechanical strength of the cage web as compared to the conventionalcross groove joint as described above.

The mechanical strength and durability of the cage is influenced by skewangle δ (see FIG. 4, for example). As the skew angle δ of the ballgrooves for the outer and inner joint members 11 and 33 increases, theball movement L22 in circumferential direction increases and the size ofcage window 44 a should also be increase to accommodate the ballmovement in the movement range. As a consequence, the thickness of cageweb 44 b between two adjacent windows 44 a becomes smaller as the skewangle of the grooves for the inner and outer joint member increases.Therefore, considering all the factors described above, the applicant ofthe present application has discovered several effective ways to reducethe ball movements and the size of cage windows in the cross groovejoint (preferably, but not necessarily, of the type having eight or moreballs) by decreasing the skew angle and also optimizing the shapes ofthe ball grooves. In this regard, the present invention has incorporatedcomposite groove patterns (for example, such as a combination of linerand non-linear grooves, or of skewed grooves and non-linear grooves) tothe ball grooves of the outer and inner joint members. As a consequence,by applying the inventive design to the cross groove joint, thethickness of the cage web and the mechanical strength of the cage andthe joint can be increased over the conventional type joint as shown inFIG. 4, for example.

According to the present invention, in particular, as described with theeight ball type joint, for example, in order for the eight ball crossgroove joint to secure the strength and durability of the cage to thelevel similar or equivalent to that of the six ball cross groove jointhaving the same pitch circle diameter (PCD), the skew angle is minimizedand the minimum thickness (least effective thickness) of the outer andinner joint members (and thus, the thickness of the cage web as well)are maximized as compared to the conventional joint described abovewithout any degradation of functions in the joint.

According to one aspect of the present invention, a cross groove typeconstant velocity joint for a drive system comprises: an outer jointmember having a plurality of inwardly facing outer ball grooves, theouter ball grooves consisting of a first group of grooves and a secondgroup of grooves with composite or non-linear groove pattern; an innerjoint member disposed inside the outer joint member and having aplurality of outwardly facing inner ball grooves consisting of a firstgroup of grooves and a second group of grooves with composite ornon-linear groove pattern, each inner ball groove of the inner jointmember being coupled with a corresponding outer ball groove of the outerjoint member generally in crossed pair; and a cage havingcircumferentially displaced cage windows to accommodate a plurality ofballs therein. The groove patterns of the ball grooves can be acombination of skewed grooves and non-linear grooves, a combination ofnon-linear grooves such as a curved groove or a compositely shapedgroove, or a combination of linear grooves and non-linear grooves.

According to one preferred embodiment of the invention, a cross groovetype constant velocity joint for a drive system comprises: an outerjoint member having a plurality of inwardly facing outer ball grooves,the outer ball grooves consisting of a first group of grooves, eachgroove of which having a skewed groove shape with a skew angle otherthan zero and alternately arranged in opposite directions relative to anaxis of rotation of outer joint member, and a second group of grooves,each groove of which having a non-linear groove shape formed with two ormore groove segments having different skew angles relative to an axis ofrotation of outer joint member; an inner joint member disposed insidethe outer joint member and having a plurality of outwardly facing innerball grooves consisting of a first group of grooves, each groove ofwhich having a skewed groove shape with a skew angle other than zero andalternately arranged in opposite directions relative to an axis ofrotation of inner joint member, and a second group of grooves, eachgroove of which having a non-linear groove shape formed with two or moregroove segments having different skew angles relative to an axis ofrotation of inner joint member, each inner ball groove of the innerjoint member being coupled with a corresponding outer ball groove of theouter joint member generally in crossed pair; a plurality of torquetransfer balls which are guided by the ball groove faces of outer andinner joint member; and a cage having circumferentially displacedwindows to accommodate the balls therein.

According to another preferred embodiment of the invention, a crossgroove type constant velocity joint for a drive system comprises: anouter joint member having a plurality of inwardly facing outer ballgrooves, the outer ball grooves consisting of a first group of grooves,each groove of which having a skewed groove shape with a skew angleother than zero and alternately arranged in opposite directions relativeto an axis of rotation of outer joint member, and a second group ofgrooves, each groove of which having a continuously curved groove shape;an inner joint member disposed inside the outer joint member and havinga plurality of outwardly facing inner ball grooves consisting of a firstgroup of grooves, each groove of which having a skewed groove shape witha skew angle other than zero and alternately arranged in oppositedirections relative to an axis of rotation of inner joint member, and asecond group of grooves, each groove of which having a continuouslycurved groove shape, each inner ball groove of the inner joint memberbeing coupled with a corresponding outer ball groove of the outer jointmember generally in crossed pair; a plurality of torque transfer ballswhich are guided by the ball groove faces of outer and inner jointmember; and a cage having circumferentially displaced windows toaccommodate the balls therein.

According to another preferred embodiment of the invention, a crossgroove type constant velocity joint for a drive system comprises: anouter joint member having a plurality of inwardly facing outer ballgrooves, the outer ball grooves consisting of a first group of grooves,each groove of which having a continuously curved groove shape, and asecond group of grooves, each groove of which having a continuouslycurved groove shape arranged in direction opposite to the groove of thefirst group of grooves; an inner joint member disposed inside the outerjoint member and having a plurality of outwardly facing inner ballgrooves consisting of a first group of grooves, each groove of whichhaving a continuously curved groove shape, and a second group ofgrooves, each groove of which having a continuously curved groove shapearranged in direction opposite to the groove of the first group ofgrooves, each inner ball groove of the inner joint member being coupledwith a corresponding outer ball groove of the outer joint membergenerally in crossed pair; a plurality of torque transfer balls whichare guided by the ball groove faces of outer and inner joint member; anda cage having circumferentially displaced windows to accommodate theballs therein.

According to another preferred embodiment of the invention, a crossgroove type constant velocity joint for a drive system comprises: anouter joint member having a plurality of inwardly facing outer ballgrooves, the outer ball grooves consisting of a first group of grooves,each groove of which having a non-linear groove shape formed with two ormore groove segments having different skew angles relative to an axis ofrotation of outer joint member, and a second group of grooves, eachgroove of which having a non-linear groove shape formed with two or moregroove segments having different skew angles relative to an axis ofrotation of outer joint member; an inner joint member disposed insidethe outer joint member and having a plurality of outwardly facing innerball grooves consisting of a first group of grooves, each groove ofwhich having a non-linear groove shape formed with two or more groovesegments having different skew angles relative to an axis of rotation ofouter joint member, and a second group of grooves, each groove of whichhaving a non-linear groove shape formed with two or more groove segmentshaving different skew angles relative to an axis of rotation of innerjoint member, each inner ball groove of the inner joint member beingcoupled with a corresponding outer ball groove of the outer joint membergenerally in crossed pair; a plurality of torque transfer balls whichare guided by the ball groove faces of outer and inner joint member; anda cage having circumferentially displaced windows to accommodate theballs therein.

BRIEF DESCRIPTION OF THE DRAWINGS

The above described and other objects, features and advantages of thepresent invention will be more apparent from the presently preferredembodiments of the invention disclosed in the following description andillustrated in the accompanying drawings, in which:

FIG. 1( a) is a view illustrating a conventional cross groove joint withsix balls;

FIG. 1( b) is a cross-sectional view of the conventional cross groovejoint as shown in FIG. 1( a), taken along line A-A in the figure;

FIGS. 2( a)-2(c) are, respectively, a view of a conventional crossgroove joint with six balls, a partial side view thereof forillustrating the shapes of the ball grooves in the outer and inner jointmembers and movements of the balls in the grooves, and a partial sideview for illustrating movements of the balls in the cage;

FIG. 3( a) is a view illustrating a conventional cross groove joint witheight balls;

FIG. 3( b) is a cross-sectional view of the conventional cross groovejoint as shown in FIG. 3( a), taken along line B-B in the figure;

FIGS. 4( a)-4(c) are, respectively, a view of a conventional crossgroove joint with eight balls, a partial side development (i.e.,deployed or radially projected) view thereof for illustrating the shapesof the ball grooves in the outer and inner joint members and movementsof the balls in the grooves, and a partial side view for illustratingmovements of the balls in the cage;

FIGS. 5( a)-5(c) are, respectively, a view of the cross groove typeconstant velocity joint with eight balls, constructed according to onepreferred embodiment of the present invention, a side cross-sectional,development view (i.e., deployed or radially projected on a plane) ofthe outer joint member thereof, and a side cross-sectional developmentview of the inner joint member thereof;

FIGS. 6( a)-6(c) are, respectively, a view of the cross groove typeconstant velocity joint with eight balls, constructed according toanother preferred embodiment of the present invention, a sidecross-sectional and development view of the outer joint member thereof,and a side cross-sectional and development view of the inner jointmember thereof;

FIGS. 7( a)-7(c) are, respectively, a view of the cross groove typeconstant velocity joint with eight balls, constructed according toanother preferred embodiment of the present invention, a sidecross-sectional and development view of the outer joint member thereof,and a side cross-sectional and development view of the inner jointmember thereof;

FIGS. 8( a)-8(c) are, respectively, a view of the cross groove typeconstant velocity joint with eight balls, constructed according toanother preferred embodiment of the present invention, a sidecross-sectional and development view of the outer joint member thereof,and a side cross-sectional and development view of the inner jointmember thereof;

FIGS. 9( a)-9(c) are, respectively, a view of the cross groove typeconstant velocity joint with eight balls, constructed according toanother preferred embodiment of the present invention, a sidecross-sectional and development view of the outer joint member thereof,and a side cross-sectional and development view of the inner jointmember thereof; and

FIGS. 10( a)-10(c) are, respectively, a view of the cross groove typeconstant velocity joint with eight balls, constructed according toanother preferred embodiment of the present invention, a sidecross-sectional and development view of the outer joint member thereof,and a side cross-sectional and development view of the inner jointmember thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be explained and illustrated below inassociation with several embodiments to be described later, inparticular, the cross groove joint of eight ball type. However, it isnoted that the present invention is not limited to the eight ball typejoint, but is applicable to the cross groove joint of any ball type, forexample, having six, eight, ten, or more balls.

Referring to FIGS. 5-10 of the drawings, the cross groove type constantvelocity joints of the present invention are described herein in detailswith several exemplary or preferred embodiments thereof. However, thefollowing descriptions of such embodiments are intended primarily forillustrating the principles and exemplary constructions of the constantvelocity joints of the present invention, and the present invention isnot specifically limited to these exemplary embodiments. Thus, oneskilled in the art can appreciate or recognize that variousmodifications and substitutions can be made thereto without departingfrom the spirit and scope of the present invention.

Throughout the description of the present application, common or similarelements are to be referred with the same or similar referencecharacters for simplicity purposes.

With reference to FIG. 5, one preferred embodiment of the presentinvention is described below in details. In this embodiment, the crossgroove joint includes an outer joint member 31 having a plurality of(i.e., eight) inwardly facing outer ball grooves 31 a-31 h, and an innerjoint member 33 placed inside the outer joint member 31 and having aplurality of (i.e., eight) outwardly facing inner ball grooves 33 a-33h. The corresponding outer and inner ball grooves 31 a-31 h and 33 a-33h face each other in pairs with each of the eight balls (not shown inFIG. 5) retained between each pair for torque transfer between the innerand outer joint members 31 and 33. The cross groove joint furtherincludes a cage (not shown in FIG. 5) containing eight cage windows (notshown in FIG. 5) for retaining the balls therein and to transmit therotational torque between the outer and inner joint members as issimilar to that shown in FIG. 4. However, unlike the conventional crossgroove joint as shown in FIG. 4, having the grooves alternately disposedin opposite directions with the same inclination angle δ, the ballgrooves 31 a-31 h and 33 a-33 h of the outer and inner joint membershave composite or complex shapes as shown in FIGS. 5( b) and 5(c).

More specifically, in the present embodiment the shapes of the ballgrooves are differentiated in two groups as illustrated in FIG. 5. Inparticular, a first group of grooves, namely, four ball grooves 31 a, 31c, 31 e, 31 g of the outer joint member 31 (displaced to each other withthe phase angle of 90 degree) and four ball grooves 33 a, 33 c, 33 e, 33g of the inner joint member 33 (displaced to each other with the phaseangle of 90 degree) each have a skewed groove with a skew angle δ1throughout the length of the groove, but alternately arranged inopposite directions. On the other hand, a second group of grooves,namely, the remaining four ball grooves 31 b, 31 d, 31 f, 31 h of theouter joint member 31 and the remaining four ball grooves 33 b, 33 d, 33f, 33 h of the inner joint member 33 each have a composite groove shapewhich consists of a straight groove segment ST from the groove center LCto one end of groove and a skewed groove segment SK from the groovecenter LC to the other end of groove, each with a skew angle δ2 butarranged alternately in opposite directions. Here, the skew angle δ2 maybe selected to have an angle the same as or less than δ1 which is inturn selectable depending on the desired design of the joint system, andgenerally, in the range between 5 degree and 20 degree. With such acomposite groove configuration, combined with a skewed groove and agroove having the straight groove segments ST and the skewed groovesegments SK with appropriate skew angle δ, the minimum thickness (theleast effective thickness) LL of the outer and inner joint members 31and 33 can be increased than that of the conventional cross groove jointas shown in FIG. 4. As a result, the ball movements in the cross groovejoint and the size of cage windows can be reduced, while enlarging thethickness of cage webs as compared to that shown in FIG. 4. Accordingly,the cross groove joint of the present embodiment can enhance themechanical strength and durability of the joint as compared to theconventional joint.

With reference to FIG. 6, another preferred embodiment of the presentinvention is described below in details. The basic structure of thisjoint is similar to that described shown in association with FIG. 5above, and detailed descriptions regarding to the common elements andstructure of this embodiment are to be omitted herein for simplicitypurposes, and to be referred above.

As is similar to the previous embodiment of FIG. 5, and unlike theconventional cross groove joint as shown in FIG. 4 (which has thegrooves alternately disposed in opposite directions with the sameinclination angle δ), the ball grooves 31 a-31 h and 33 a-33 h of theouter and inner joint members of the present embodiment have compositeor complex shapes, in different pattern, as shown in FIGS. 6( b) and6(c).

More specifically, in this embodiment as illustrated in FIG. 6, a firstgroup of grooves, namely, four ball grooves 31 a, 31 c, 31 e, 31 g ofthe outer joint member 31 (displaced to each other with the phase angleof 90 degree) and four ball grooves 33 a, 33 c, 33 e, 33 g of the innerjoint member 33 (displaced to each other with the phase angle of 90degree) each have a skewed groove with a skew angle δ1 throughout thelength of the groove, but alternately arranged in opposite directions.On the other hand, a second group of grooves, namely, the remaining fourball grooves 31 b, 31 d, 31 f, 31 h of the outer joint member 31 and theremaining four ball grooves 33 b, 33 d, 33 f, 33 h of the inner jointmember 33 each have a composite groove shape which consists of astraight groove segment ST at the central area relative to the groovecenter LC and skewed groove segments SK1 and SK2 at the both end regionsof the groove, each with a skew angle δ2 but arranged alternately inopposite directions as shown. Here, the skew angle δ2 may be selected tohave an angle the same as or less than δ1 which is in turn selectabledepending on the desired design of the joint system, and generally, inthe range between 5 degree and 20 degree. With such a composite grooveconfiguration as shown, combined with a first group of grooves ofalternately-arranged skewed groove and a second group of groovescomposed of the straight groove segments ST and the skewed groovesegments SK at either or both ends of the groove, the minimum thickness(least effective thickness) LL of the outer and inner joint members 31and 33 can be increased to that of the conventional cross groove jointas shown in FIG. 4. As a result, the ball movements in the cross groovejoint and the size of cage windows can be reduced, while enlarging thethickness of cage webs as compared to that shown in FIG. 4. Accordingly,the cross groove joint of the present embodiment can enhance themechanical strength and durability of the joint as compared to theconventional joint.

With reference to FIG. 7, another preferred embodiment of the presentinvention is described below in details. The basic structure of thisjoint is similar to that described shown in association with FIG. 5above, and detailed descriptions regarding to the common elements andstructure of this embodiment are to be omitted herein for simplicitypurposes, and to be referred above.

As is similar to the previous embodiments of FIGS. 5-6, and unlike theconventional cross groove joint as shown in FIG. 4 (which has thegrooves alternately disposed in opposite directions with the sameinclination angle δ), the ball grooves 31 a-31 h and 33 a-33 h of theouter and inner joint members of the present embodiment have compositeor complex shapes, in different pattern, as shown in FIGS. 7( b) and7(c).

More specifically, in this embodiment as illustrated in FIG. 7, a firstgroup of grooves, namely, four ball grooves 31 a, 31 c, 31 e, 31 g ofthe outer joint member 31 (displaced to each other with the phase angleof 90 degree) and four ball grooves 33 a, 33 c, 33 e, 33 g of the innerjoint member 33 (displaced to each other with the phase angle of 90degree) each have a skewed groove with a skew angle δ1 throughout thelength of the groove, but alternately arranged in opposite directions.On the other hand, a second group of grooves, namely, the remaining fourball grooves 31 b, 31 d, 31 f, 31 h of the outer joint member 31 and theremaining four ball grooves 33 b, 33 d, 33 f, 33 h of the inner jointmember 33 each have a curved groove with a skew angle δ2 with a radius Rcentered on the normal line relatively to the skew angle line at thecenter, but arranged alternately in opposite directions as shown. Here,the skew angle δ2 may be selected to have an angle the same as or lessthan δ1 which is in turn selectable depending on the desired design ofthe joint system, and generally, in the range between 5 degree and 20degree. With such a composite groove configuration as shown, combinedwith a first group of grooves of alternately-arranged skewed grooves anda second group of grooves of alternately-arranged curved grooves, theminimum thickness (least effective thickness) LL of the outer and innerjoint members 31 and 33 can be increased to that of the conventionalcross groove joint as shown in FIG. 4. As a result, the ball movementsin the cross groove joint and the size of cage windows can be reduced,while enlarging the thickness of cage webs as compared to that shown inFIG. 4. Accordingly, the cross groove joint of the present embodimentcan enhance the mechanical strength and durability of the joint ascompared to the conventional joint.

With reference to FIG. 8, another preferred embodiment of the presentinvention is described below in details. The basic structure of thisjoint is similar to that described shown in association with FIG. 5above, and detailed descriptions regarding to the common elements andstructure of this embodiment are to be omitted herein for simplicitypurposes, and to be referred above.

As is similar to the previous embodiments of FIGS. 5-7, and unlike theconventional cross groove joint as shown in FIG. 4 (which has thegrooves alternately disposed in opposite directions with the sameinclination angle δ), the ball grooves 31 a-31 h and 33 a-33 h of theouter and inner joint members of the present embodiment have compositeor complex shapes, in different pattern, as shown in FIGS. 8( b) and8(c).

More specifically, in this embodiment as illustrated in FIG. 8, a firstgroup of grooves, namely, four ball grooves 31 a, 31 c, 31 e, 31 g ofthe outer joint member 31 (displaced to each other with the phase angleof 90 degree) and four ball grooves 33 a, 33 c, 33 e, 33 g of the innerjoint member 33 (displaced to each other with the phase angle of 90degree) each have a linear or straight groove with no skew angle. On theother hand, a second group of grooves, namely, the remaining four ballgrooves 31 b, 31 d, 31 f, 31 h of the outer joint member 31 and theremaining four ball grooves 33 b, 33 d, 33 f, 33 h of the inner jointmember 33 each have a curved groove with a skew angle δ with a radius Rcentered on the normal line relatively to the skew angle line at thecenter, which are arranged alternately in opposite directions as shown.Here, the skew angle δ may be selected depending on the desired designof the joint system, and generally, in the range between 5 degree and 20degree. With such a composite groove configuration as shown, combinedwith a first group of grooves of linear grooves and a second group ofgrooves of alternately-arranged curved grooves, the minimum thickness(least effective thickness) LL of the outer and inner joint members 31and 33 can be increased to that of the conventional cross groove jointas shown in FIG. 4. As a result, the ball movements in the cross groovejoint and the size of cage windows can be reduced, while enlarging thethickness of cage webs as compared to that shown in FIG. 4. Accordingly,the cross groove joint of the present embodiment can enhance themechanical strength and durability of the joint as compared to theconventional joint.

With reference to FIG. 9, another preferred embodiment of the presentinvention is described below in details. The basic structure of thisjoint is similar to that described shown in association with FIG. 5above, and detailed descriptions regarding to the common elements andstructure of this embodiment are to be omitted herein for simplicitypurposes, and to be referred above.

As is similar to the previous embodiments of FIGS. 5-8, and unlike theconventional cross groove joint as shown in FIG. 4 (which has thegrooves alternately disposed in opposite directions with the sameinclination angle δ), the ball grooves 31 a-31 h and 33 a-33 h of theouter and inner joint members of the present embodiment have compositeor complex shapes, in different pattern, as shown in FIGS. 9( b) and9(c).

More specifically, in this embodiment as illustrated in FIG. 9, fourball grooves 31 a, 31 c, 31 e, 31 g of the outer joint member 31(displaced to each other with the phase angle of 90 degree) and fourball grooves 33 a, 33 c, 33 e, 33 g of the inner joint member 33(displaced to each other with the phase angle of 90 degree) each have acurved groove with a skew angle δwith a radius R centered on the normalline relatively to the skew angle line at the center. On the other hand,the remaining four ball grooves 31 b, 31 d, 31 f, 31 h of the outerjoint member 31 and the remaining four ball grooves 33 b, 33 d, 33 f, 33h of the inner joint member 33 each have a similarly curved groove withthe skew angle δ with a radius R centered on the normal line relativelyto the skew angle line at the center, but arranged in direction oppositeto the first group of grooves described above. Here, the degree of theskew angle δ is selectable depending on the desired design of the jointsystem, generally, in the range between 5 degree and 20 degree. Withsuch a composite groove configuration, having the oppositely orientedcurved grooves in alternate arrangement and with appropriate skew angleδ, the minimum thickness (least effective thickness) LL of the outer andinner joint members 31 and 33 can be increased to that of theconventional cross groove joint as shown in FIG. 4. As a result, theball movements in the cross groove joint and the size of cage windowscan be reduced, while enlarging the thickness of cage webs as comparedto that shown in FIG. 4. Accordingly, the cross groove joint of thepresent embodiment can enhance the mechanical strength and durability ofthe joint as compared to the conventional joint.

With reference to FIG. 10, another preferred embodiment of the presentinvention is described below in details. The basic structure of thisjoint is similar to that described and shown in association with FIG. 5above, and detailed descriptions regarding to the common elements andstructure of this embodiment are to be omitted herein for simplicitypurposes, and to be referred above.

As is similar to the previous embodiment of FIGS. 5-9 and unlike theconventional cross groove joint as shown in FIG. 4 (which has thegrooves alternately disposed in opposite directions with the sameinclination angle δ), the ball grooves 31 a-31 h and 33 a-33 h of theouter and inner joint members of the present embodiment have compositeor complex shapes, in different pattern, as shown in FIGS. 10( b) and10(c).

More specifically, in this embodiment, a first group of grooves, namely,four ball grooves 31 a, 31 c, 31 e, 31 g of the outer joint member 31(displaced to each other with the phase angle of 90 degree) and fourball grooves 33 a, 33 c, 33 e, 33 g of the inner joint member 33(displaced to each other with the phase angle of 90 degree) each have acomposite groove shape which consists of a straight groove segment STfrom the groove center LC to one end of groove and a skewed groovesegment SK from the groove center LC to the other end of groove, eachwith a skew or inclination angle δ but arranged alternately in oppositedirections. On the other hand, a second group of grooves, namely, theremaining four ball grooves 31 b, 31 d, 31 f, 31 h of the outer jointmember 31 and the remaining four ball grooves 33 b, 33 d, 33 f, 33 h ofthe inner joint member 33 each have a composite groove shape having astraight portion ST and a skewed portion SK with the same skew angle δ,but arranged in opposite directions with respect to the groove center LCrelatively to the above-identified first group of grooves. Here, thedegree of the skew angle δ is to be selected depending on the desireddesign of the joint system, generally, in the range between 5 degree and20 degree. With such a composite groove configuration having thestraight groove segments ST and the skewed groove segments SK withappropriate skew angle δ, the minimum thickness (the least effectivethickness) LL of the outer and inner joint members 31 and 33 can beincreased to that of the conventional cross groove joint as shown inFIG. 4. As a result, the ball movements in the cross groove joint andthe size of cage windows can be reduced, while enlarging the thicknessof cage webs as compared to that shown in FIG. 4. Accordingly, the crossgroove joint of the present embodiment can enhance the mechanicalstrength and durability of the joint as compared to the conventionaljoint.

As described above in connection with several exemplary embodimentsthereof, in order to provide an enhanced strength to the cage web andthe cross groove joint, the present invention provides a cross groovejoint including an outer joint member with a plurality of inwardlyfacing ball grooves and an inner joint member with a plurality ofoutwardly facing ball grooves, in which the shapes of the ball groovesof the outer and inner joint member are configured to increase thethickness and also the mechanical strength of the cage web as comparedto the conventional cross groove joint, in particular, by applyingcomposite and/or non-linear groove patterns to the ball grooves invarious different patterns as illustrated with several embodiments asexamples.

The above disclosed embodiments of the invention are representatives ofa presently preferred form of the invention, but are intended to beillustrative rather than definitive thereof. Accordingly, those skilledin the art will appreciate or recognize that various modifications andsubstitutions can be made thereto without departing from the spirit andscope of the present invention as set forth in the appended claims.

1. A constant velocity joint for a drive system comprising: an outerjoint member having a plurality of inwardly facing outer ball grooves,the outer ball grooves consisting of a first group of grooves, eachgroove of which having a skewed groove shape with a skew angle otherthan zero and alternately arranged in opposite directions relative to anaxis of rotation of outer joint member, and a second group of grooves,each groove of which having a non-linear groove shape formed with two ormore groove segments having different skew angles relative to an axis ofrotation of outer joint member; an inner joint member disposed insidethe outer joint member and having a plurality of outwardly facing innerball grooves consisting of a first group of grooves, each groove ofwhich having a skewed groove shape with a skew angle other than zero andalternately arranged in opposite directions relative to an axis ofrotation of inner joint member, and a second group of grooves, eachgroove of which having a non-linear groove shape formed with two or moregroove segments having different skew angles relative to an axis ofrotation of inner joint member, each inner ball groove of the innerjoint member being coupled with a corresponding outer ball groove of theouter joint member generally in crossed pair; a plurality of torquetransfer balls which are guided by the ball groove faces of outer andinner joint member; and a cage having circumferentially displacedwindows to accommodate the balls therein.
 2. The constant velocity jointof claim 1, wherein the first group of grooves of the outer and innerjoint members, respectively, consist of four ball grooves displaced toone another with a phase angle of 90 degree, and the second group ofgrooves of the outer and inner joint members, respectively, consist offour ball grooves displaced to one another with a phase angle of 90degree.
 3. The constant velocity joint of claim 1, wherein each grooveof the second group of grooves of the outer and inner joint members isformed with two groove segments, one with a straight groove segmenthaving no skew angle, which is formed from the center of the groove toone end of the groove, and the other with a skewed groove segment havinga skew angle other than zero, which is formed from the center of thegroove to the other end of the groove.
 4. The constant velocity joint ofclaim 1, wherein each groove of the second group of grooves of the outerand inner joint members is formed with three groove segments, a firstsegment with a straight groove segment having no skew angle, which isformed adjacent to the center of the groove, a second segment with askewed groove segment having a skew angle other than zero, which isformed adjacent to one end of the groove, and a third segment with askewed groove segment having a skew angle other than zero, which isformed adjacent to the other end of the groove and in direction oppositeto the second segment.
 5. The constant velocity joint of claim 1,wherein the number of the torque transfer balls is an even number.
 6. Aconstant velocity joint for a drive system comprising: an outer jointmember having a plurality of inwardly facing outer ball grooves, theouter ball grooves consisting of a first group of grooves, each grooveof which having a skewed groove shape with a skew angle other than zeroand alternately arranged in opposite directions relative to an axis ofrotation of outer joint member, and a second group of grooves, eachgroove of which having a continuously curved groove shape; an innerjoint member disposed inside the outer joint member and having aplurality of outwardly facing inner ball grooves consisting of a firstgroup of grooves, each groove of which having a skewed groove shape witha skew angle other than zero and alternately arranged in oppositedirections relative to an axis of rotation of inner joint member, and asecond group of grooves, each groove of which having a continuouslycurved groove shape, each inner ball groove of the inner joint memberbeing coupled with a corresponding outer ball groove of the outer jointmember generally in crossed pair; a plurality of torque transfer ballswhich are guided by the ball groove faces of outer and inner jointmember; and a cage having circumferentially displaced windows toaccommodate the balls therein.
 7. The constant velocity joint of claim6, wherein the continuously curved groove shape of the second group ofgrooves of the outer and inner joint members is a circular shape with aradius and a skew angle other than zero at the center of the groove. 8.The constant velocity joint of claim 6, wherein the first group ofgrooves of the outer and inner joint members, respectively, consist offour ball grooves displaced to one another with a phase angle of 90degree, and the second group of grooves of the outer and inner jointmembers, respectively, consist of four ball grooves displaced to oneanother with a phase angle of 90 degree.
 9. The constant velocity jointof claim 6, wherein the number of the torque transfer balls is an evennumber.
 10. A constant velocity joint for a drive system comprising: anouter joint member having a plurality of inwardly facing outer ballgrooves, the outer ball grooves consisting of a first group of grooves,each groove of which having a linear or straight groove shape with noskew angle relative to an axis of rotation of outer joint member, and asecond group of grooves, each groove of which having a continuouslycurved groove shape alternately arranged in opposite directions relativeto an axis of rotation of outer joint member; an inner joint memberdisposed inside the outer joint member and having a plurality ofoutwardly facing inner ball grooves consisting of a first group ofgrooves, each groove of which having a linear or straight groove shapewith no skew angle relative to an axis of rotation of inner jointmember, and a second group of grooves, each groove of which having acontinuously curved groove shape alternately arranged in oppositedirections relative to an axis of rotation of inner joint member, eachinner ball groove of the second group of grooves of the inner jointmember being coupled with a corresponding outer ball groove of thesecond group of grooves of the outer joint member generally in crossedpair; a plurality of torque transfer balls which are guided by the ballgroove faces of outer and inner joint member; and a cage havingcircumferentially displaced windows to accommodate the balls therein.11. The constant velocity joint of claim 10, wherein the continuouslycurved groove shape of the second group of grooves of the outer andinner joint members is a circular shape with a radius and a skew angleother than zero at the center of the groove.
 12. The constant velocityjoint of claim 10, wherein the first group of grooves of the outer andinner joint members, respectively, consist of four ball groovesdisplaced to one another with a phase angle of 90 degree, and the secondgroup of grooves of the outer and inner joint members, respectively,consist of four ball grooves displaced to one another with a phase angleof 90 degree.
 13. The constant velocity joint of claim 10, wherein thenumber of the torque transfer balls is an even number.
 14. A constantvelocity joint for a drive system comprising: an outer joint memberhaving a plurality of inwardly facing outer ball grooves, the outer ballgrooves consisting of a first group of grooves, each groove of whichhaving a continuously curved groove shape, and a second group ofgrooves, each groove of which having a continuously curved groove shapearranged in direction opposite to the groove of the first group ofgrooves; an inner joint member disposed inside the outer joint memberand having a plurality of outwardly facing inner ball grooves consistingof a first group of grooves, each groove of which having a continuouslycurved groove shape, and a second group of grooves, each groove of whichhaving a continuously curved groove shape arranged in direction oppositeto the groove of the first group of grooves, each inner ball groove ofthe inner joint member being coupled with a corresponding outer ballgroove of the outer joint member generally in crossed pair; a pluralityof torque transfer balls which are guided by the ball groove faces ofouter and inner joint member; and a cage having circumferentiallydisplaced windows to accommodate the balls therein.
 15. The constantvelocity joint of claim 14, wherein the continuously curved groove shapeof the first and second group of grooves of the outer and inner jointmembers is a circular shape with a radius and a skew angle other thanzero at the center of the groove.
 16. The constant velocity joint ofclaim 14, wherein the first group of grooves of the outer and innerjoint members, respectively, consist of four ball grooves displaced toone another with a phase angle of 90 degree, and the second group ofgrooves of the outer and inner joint members, respectively, consist offour ball grooves displaced to one another with a phase angle of 90degree.
 17. The constant velocity joint of claim 14, wherein the numberof the torque transfer balls is an even number.
 18. A constant velocityjoint for a drive system comprising: an outer joint member having aplurality of inwardly facing outer ball grooves, the outer ball groovesconsisting of a first group of grooves, each groove of which having anon-linear groove shape formed with two or more groove segments havingdifferent skew angles relative to an axis of rotation of outer jointmember, and a second group of grooves, each groove of which having anon-linear groove shape formed with two or more groove segments havingdifferent skew angles relative to an axis of rotation of outer jointmember; an inner joint member disposed inside the outer joint member andhaving a plurality of outwardly facing inner ball grooves consisting ofa first group of grooves, each groove of which having a non-lineargroove shape formed with two or more groove segments having differentskew angles relative to an axis of rotation of outer joint member, and asecond group of grooves, each groove of which having a non-linear grooveshape formed with two or more groove segments having different skewangles relative to an axis of rotation of inner joint member, each innerball groove of the inner joint member being coupled with a correspondingouter ball groove of the outer joint member generally in crossed pair; aplurality of torque transfer balls which are guided by the ball groovefaces of outer and inner joint member; and a cage havingcircumferentially displaced windows to accommodate the balls therein.19. The constant velocity joint of claim 18, wherein the first group ofgrooves of the outer and inner joint members, respectively, consist offour ball grooves displaced to one another with a phase angle of 90degree, and the second group of grooves of the outer and inner jointmembers, respectively, consist of four ball grooves displaced to oneanother with a phase angle of 90 degree.
 20. The constant velocity jointof claim 18, wherein each groove of the first and second group ofgrooves of the outer and inner joint members is formed with two groovesegments, one with a straight groove segment having no skew angle, whichis formed from the center of the groove to one end of the groove, andthe other with a skewed groove segment having a skew angle other thanzero, which is formed from the center of the groove to the other end ofthe groove.
 21. The constant velocity joint of claim 18, wherein thenumber of the torque transfer balls is an even number.